1. Field of the Invention
The present invention relates to an ink ribbon cartridge that prevents reverse rotation of spools that hold an ink ribbon wound thereabout.
2. Description of the Related Art
Thermal transfer printer apparatuses use an ink ribbon cartridge. An ink ribbon cartridge containing an ink ribbon is installed in a thermal transfer printer apparatus, in which the ink ribbon and printing paper are driven to travel between a thermal head and a platen roller provided in a position opposite to the thermal head. In addition, thermal energy is applied by the thermal head to the ink ribbon, and dies of the ink ribbon are thermally transferred, whereby an image is printed on the printing paper. An ink ribbon cartridge used by being installed in a thermal transfer printer apparatus, such as described above, includes an ink ribbon that includes respective ink layers of colors, such as yellow, magenta, and cyan, that are juxtaposed to one another in a travel direction. The ink ribbon is wounded on a pair of spools, namely, a supply spool and a take-up spool, and the pair of spools holding the wounded ink ribbon are rotatably housed in a cartridge body. Such the ink ribbon cartridge includes a non-reversing mechanism to prevent reverse rotation of one or both of the spools during, for example, transportation or storage.
For example, Japanese Unexamined Patent Application Publication No. 08-244322 (“Patent Publication 1,” hereafter) discloses an ink ribbon cartridge that includes a ratchet gear in one end portion of a spool that holds an ink ribbon wound thereabout, and pawls that engages the ratchet gear in the event of reverse rotation. However, in the ink ribbon cartridge described in Patent Publication 1, during forward rotation of the spool for printing, there occurs operational noise, i.e., vibration noise, of the pawls riding over gear teeth of the ratchet gear. According to description of Patent Publication 1, an adhesive made of, for example, a plastic film is provided to prevent the operational noise. With the adhesive used, while the operational noise can be restrained from occurring, the number of components/parts is increased thereby, such that an assembly step become complex.
In addition, Japanese Unexamined Patent Application Publication No. 11-115267 (“Patent Publication 2,” hereafter) discloses an ink ribbon cartridge that includes pawls for engagement with a ratchet gear of a spool. However, similar to the above, also in the ink ribbon cartridge described in Patent Publication 2, during forward rotation of a spool for printing, there occurs operational noise, i.e., vibration noise, of the pawls riding over gear teeth of the ratchet gear. Further, in the ink ribbon cartridge disclosed in patent publication 2, the pawls are separate members from the body of the cartridge, the number of components/parts is increased thereby, such that an assembly step become complex.
Further, there are ink ribbon cartridges of another including irregular portions provided on an end face of the spool. In this case, the irregular portions of the spool end face are urged by a leaf spring or the like provided in the cartridge body to engage irregular portions on an opposite face of the cartridge body, thereby to prevent rotation of the spool. In the ink ribbon cartridge also, since the leaf spring is used, the number of components/parts cannot be reduced.